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  1. #1
    Join Date
    Apr 2006
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    Single Evap Hot Gas Defrosting.



    When we use hot gas defrosting with single evap, some liquid flows back during defrost, which opens the oil level monitor control, as refn flushes the oil and control shows no oil condition.

    Even when bigger accumulators are used, the problem still persists.

    Any Suggestion???



  2. #2
    mr superheat's Avatar
    mr superheat Guest

    Re: Single Evap Hot Gas Defrosting.

    is the system hot gas defrost or reverse cycle? if your system is one comp, one cond, one cooler surely it must be reverse cycle - please clarify and i may be able to help. One thing is for sure adding larger accumulators isnt the answer my friend

  3. #3
    Join Date
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    Re: Single Evap Hot Gas Defrosting.

    It is NOT a reverse cycle but just a 3 pipe hot gas defrost system. I can see that larger accumulators are not doing the job.

    Appreciate your help!!

  4. #4
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    Re: Single Evap Hot Gas Defrosting.

    jwasir.
    You could always fit a solenoid valve in the oil return line which is powered through NO axillary contact on the comp run contactor.
    Add a delay on timer and your system should be nice and warm before any nasty liquid is returned to the comp sump.
    Without seeing your actual set-up I cannot advise further at this stage.
    But basically you need to prevent the liquid returning via the oil return line and something like I have suggested should do the trick?
    Grizzly

  5. #5
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    Re: Single Evap Hot Gas Defrosting.

    Have you checked the 3 way valve solenoid with a magnet sometimes the slide sticks. My be way off here

  6. #6
    Join Date
    Dec 2007
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    Re: Single Evap Hot Gas Defrosting.

    jwasir,
    Can you please explain how single hot gas defrost works?

    Where does compressor get its gas to generate hot gas?

  7. #7
    Join Date
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    Re: Single Evap Hot Gas Defrosting.

    Hi Ranger.
    I have similar questions,
    OIL lines with liquid refrigerant usually are connected to the oil separator on the discharge side.
    Whereas liquid returning from the evap is on the suction side.
    If the issue is with the discharge side I would consider what I have said about a solenoid valve and question the operation of the non return valve in the discharge line?
    Whereas if there is liquid flooding back into the sump?
    I would question the metering of the hot gas vapour into the suction line IE is a pm valve used and set correctly?
    I think we all need a bit more info.
    Grizzly

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